Myocardial 123I-MIBG scintigraphy predicts an impairment in myocardial functional reserve during dobutamine stress in patients with idiopathic dilated cardiomyopathy

Purpose

We investigated whether myocardial ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG) scintigraphy predicts impairment of myocardial functional reserve in response to dobutamine stress in patients with idiopathic dilated cardiomyopathy (DCM).

Methods

Forty DCM patients (LVEF 39?±?12 %) underwent myocardial ¹²³I-MIBG scintigraphy, echocardiography, and cardiac catheterization. Myocardial ¹²³I-MIBG uptake was quantified as the delayed heart to mediastinum (H/M) ratio and washout rate (WR). Local denervation was evaluated on polar map images. LV dP/dt _max and T_1/2 were determined from left ventricular pressure curves at baseline and during dobutamine infusion (15 μg/kg?/min). Patients were classified into two groups as follows: group A comprised 21 patients showing a delayed H/M ratio of <1.9 (median value); group B comprised 19 patients showing a delayed H/M ratio of ≥1.9.

Results

The percentage change in heart rate (%HR), LV dP/dt _max (%LV dP/dt _max), and T _1/2 (%T _1/2) from baseline to dobutamine stress were significantly more reduced in group A than in group B (39.3?±?20.2 %, 55.2?±?24.1 %, p?p?p?r?=?0.35, p?P/dt _max (r?=?0.45, p?T _1/2 (r?=?0.34, p?r?=??0.37, p?P/dt _max (r?=??0.60, p?T _1/2 (r?=??0.34, p?Conclusion Reduced ¹²³I-MIBG uptake and increased washout were related to impairment in adrenergic myocardial functional reserve in idiopathic DCM.